The present invention relates generally to solid-state electronics, and more specifically to an electrically programmable, non-volatile resistive memory.
Electronic memories are integral to computer systems and many electronic circuits. Continuous improvements in the operating speed and computing power of central processing units (CPUs) have enabled the operation of an increasing variety of applications, many of which require larger and faster memories. Larger memories are characterized by having more memory cells to store more bits of data.
Memories may be fabricated using various technologies. A new memory technology that has gain considerable interest uses materials having a perovskite structure to form thin film resistive elements. These resistive elements have multiple stable resistance states and may be used as non-volatile memory elements for memory cells. Each resistive element may be (1) programmed to a high resistance state by applying a narrow electric pulse and (2) programmed (or “erased”) to a low resistance state by applying either a narrow electric pulse of an opposite polarity or a wide electric pulse of the same polarity but lower amplitude. The resistance state of each resistive element may thereafter be sensed to determine the logic value of the corresponding memory cell.
A memory array may be efficiently fabricated with resistive elements formed with a perovskite material. Such a memory array also has other desirable characteristics such as (1) ease of decoding to select memory cells for reading, programming, and erasing, (2) ease of programming and erase of the resistive elements, and so on. However, the structure of the memory array is such that a leakage path exists for each resistive element, as described below. The leakage paths of unselected resistive elements can adversely affect the reading and possibly the programming and erase of selected resistive elements.
There is therefore a need in the art for a non-volatile resistive memory having good memory cell isolation for proper reading, programming, and erase of the resistive elements.